Faceting machine



April 22,1969 R.W.BVAILEY 3,439,456

FACE'IING MACHINE Filed Jan. 21, 1966 Sheet o INVENTOR For BIO/4f 5 KM,W M

ATTORNEYS April 22, 9 R. w. BAILEY 3,439,456

FACEZTINC; MACHINE Filed Jan. 21. 1966 sheet bf 2 I luvsu lqk For 12 Beat? 8) M, Km.

ATTORNEYS United States Patent 3,439,456 FACETING MACHINE Roy W. Bailey, 23517 Little Mack, St. Clair Shores, Mich. 48080 Filed Jan. 21, 1966, Ser. No. 522,204 Int. Cl. B24b 7/ 00, 9/00, 19/00 US. Cl. 51--125 6 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a faceting machine for gem stones. In the forming of facets on semiprecious and precious stones, historically the facets have been applied by hand grinding or cutting which requires great skill. In recent years, it has become more common to utilize a machine for holding the gem stones so that the facets may be cut in a more precise manner and by persons who may have less training than that required for the hand cutting. In this connection, a machine with a rotating lapping or grinding wheel is provided with a standard adjacent the wheel for supporting a holding device which permits the stone to be applied to the flat surface of the wheel. This method has worked well for round gem stones, but the problem of cutting irregular shape gem stones of the marquise or oval type has still required the hand operation.

It is an object of the present invention to provide a device which permits precision cutting of the oval type gem stone with adequate adjustment to permit suitable flexibility in the design sought.

In the machine of the present invention, the gem stone is mounted on a spindle adapted to turn on a horizontal and vertical axis and can also be shifted transversely of the main spindle axis to obtain the desired position for the oval faceting.

It is a further object of the invention to provide a relatively simple but versatile attachment for a stone cutting apparatus which permits the adaptation to oval gem stones.

Other objects and features of the invention and the principles of operation of the device will be found in the following description and claims.

Drawings accompanying the disclosure and the various views thereof may be briefly described as:

FIGURE 1, a perspective view of the assembled gem cutting apparatus.

FIGURE 2, a top view of a so-called oval or marquise type of stone showing one design of desired faceting.

FIGURE 3, a side view of the stone of FIGURE 2.

FIGURE 4, an enlarged perspective view of the gem holding arm.

FIGURE 5, a side elevation of the distal end of the gem holding arm.

FIGURE 6, a sectional view of the structure taken on line 66 of FIGURE 5.

FIGURE 7, a sectional view taken on line 7-7 of FIGURE 5.

Referring to the drawings:

The machine consists of a cast base plate 10 mounted by foot portions 12 on a baseboard 14 on which is also mounted a motor M having a control switch box 16 with a suitable outlet socket 18 for a light. On the plate 10 is mounted a vertical bearing housing 20 for containing a precision bronze bearing for suitably mounting a turntable carrying an abrasion or polishing wheel 22 which is surrounded by a suitable pan guard 24. A suitable belt 26 and pulley system 28 is utilized for driving the shaft 30 of the turntable. Supported adjustably on the plate 10 1s a mast base 32 supporting a mast 34. On the mast is mounted a yoke assembly 36 having spaced horizontal arms 38 and 40 between which is a shaft 42 (FIGURE 4) pivotally mounting a bearing socket 46 of a vertical protractor plate 44. This protractor plate is provided for giounting the gem spindle assembly for holding the gem A microadjustment nut 48 at the bottom of the shaft 42 provides a fine vertical adjustment for the protractor plate which is preferably graduated through a predetermined segment in degrees from each end, that is, to the left and right of a zero point respectively at each end (not shown). On the protractor plate- 44 is pivotally mounted on a horizontal axis a circular block 50 having a pointer plate 52 to cooperate wtih the markings on the protractor plate. The pointer plate 52 is adjustably positionable on the protractor plate and the circular block 50 is pivotally mounted on the plate 44 by a screw shaft 53 and a friction nut 54. On the perimeter of block 50 is a segmental stop block 55 which stops against the pointer plate 52. Extending radially from the circular block 50 is a spindle shaft 56 which transfixes and mounts a rectangular block 58 transversely thereto. A second block 59 is similarly mounted on spindle shaft 56 and related thereto in a manner to be explained.

Telescopically mounted on spindle shaft 56 is a hollow mount tube 57 carrying a collar 60 and index plate 61 which is preferably suitably graduated and provided with a predetermined number of teeth. Shaft 56 and tube 57 are axially related by a suitable detent and groove (not shown). These index plates can be available, for example, with 32, 60, 64, 72, and 96 teeth. The plates control the rotative position of the tube 57 on the spindle shaft 56, there being a spring biased trigger latch 64 on block 59 for controlling the position of the plate 61. Microadjusting screws 66 and 68 are provided for accurate control of the block 59 relative to plate 58.

All of the above structure is standard in connection with the mounting of a dop or a spindle shaft for the faceting of round gems. Extending downwardly from the index plate 61 is the mount tube 57 which inserts into and rigidly mounts, transversely thereof, a rectangular mounting block 74 extending to the left of the tube 57 as shown in FIGURE 5. In other words, there is an off center mount, the tube 57 having a projection 76 extending into block 74 and locked by a lock screw 78.

On one side of mounting block 74 is a side plate 80 which has a rib 82 located in a groove in block 74 and forming a dovetail groove in cooperation with a rib extension 84 on the bottom of the block 74. The plate 80 is retained and clamped on block 74 by a clamping nut 86 on screw '88. This permits the holding of a dovetail on interlock slide rib 90 on a second transverse collet block 92, the collet bloc-k 92 carrying a graduated plate 94 at the top edge thereof to permit close positioning and adjustrnent with relation to mounting block 74. At one end of collet block 92 perpendicular to the axial axis thereof and parallel to the spindle tube 57 and spindle shaft 56 is a socket recess 96- which contains a split collet sleeve 98 which can be opened and closed by small set screws 100 (FIGURE 7) in a collar 102 at the bottom of the block 92. This recess is adapted to receive the shank 104 of a dop or gem holder 106-. Small keyways 108 are provided in each side of the dop shank 104 to permit it to be located relative to the spindle and against rotation by suitable key 110.

Thus, it will be seen that it is possible to adjust the block 92 transversely of the axis of the spindle arm represented by the spindle tube 57, and the block 92 may be clamped securely in position in any olfset relationship. When the zero on plate 94' (see FIGURE 4) is coincident with the zero on block 74, the dop socket or recess 96 is on the center axis of the pivot arm. By loosening the clamp nut 86, the block 92 can be readily shifted transversely of this axis. Thus, by placing a gem in the dop head 106, it can be applied to the rotating table 22, having a suitable abrasive or polishing surface, in the various angles that are required for so-called marquise or oval grinding. The block '74 remains free to rotate in positions controlled by the index plate 61 and latch 64 about the center line of the spindle shaft 56 while the actual holding chuck can be offset to positions where the center line of the gem stone blank remains parallel with the spindle center line but revolves around the spindle center line. The offset at the point of adjustment is suitably graduated at plate 94 to indicate the amount of offset and, as has been described, can be securely locked in position. By means of this offsetting of the dop chuck, the two sides of the gem stone can be precisely ground to the required radius as in the marquise out where the width of the gem is one-half of its length, and the two sides are sections of a true circle. The keyways 8 in each side of the shaft 104 of the gem dop permit it to be rotated 180 to duplicate the form on the opposite side thereof. When the crown or portion of the gem stone above the girdle line 120' is finished, the stone may be remounted on another dop in the reverse position so that the pavilion or lower portion of the gem stone can be preformed, out and polished. This transfer and reversal of the gem stone is accomplished in a transfer fixture well known to the art which maintains the axis of the gem stone centered and true in the second dop. It also keeps the relationship to the keyway in the shank of the new dop lined up with the location in the old dop. This results in the facets on the lower part of the gem matching precisely with the facets on the upper part.

Thus, it will be seen that the offset head permits revolving of the gem about the spindle axis on a radius equal to that selected for the sides of the marquise cut. In FIGURE 2, for example, the center point A for radius R is materially offset by distance AC from the gem center C permitting the wide arc on the sides of the gem.

What is claimed as new is as follows:

1. In an apparatus for facilitating the faceting of gem stones of the type wherein a gem dop is held on a supporting spindle supported on a mast adjacent a rotating cutting wheel, that improvement for the faceting of oval stones, which comprises:

(a) a dop holder including a shank having diametrically opposed grooves extending axially thereof,

(b) a collet block rectangular in shape having a collet disposed at a right angle to the axis of the block,

(c) a means in said collet for engagement with one of the grooves in said shank to locate said shank in one of two selective positions,

(d) a mounting block rectangular in shape having a recess to receive and lock a portion of the supporting spindle in a position wherein the axis of the mounting block is disposed at a right angle to the axis of the spindle, and

(e) means adjustably associating said blocks with the axes thereof maintaining a parallel relationship for relative endwise adjustment and mutual support to a plurality of positions whereby said collet may be shifted from a position coincident with the axis of the spindle to positions wherein the axis thereof is parallel to and spaced from the axis of said spindle.

2. In an apparatus for facilitating the faceting of gem stones of the type wherein a gem dop is held on a supporting spindle on a mast adjacent a rotating cutting wheel, that improvement for the faceting of oval stones which comprises:

(a) a pair of mutually slidable blocks, one of which is mountable on a supporting spindle and relatively slidable in a direction normal to the axis of said spindle, the second of said blocks having a collet with an axis at right angles to direction of slide of said block and parallel to the axis of a supporting spindle,

(b) a dop having a shank receivable in said collet, and

(c) means at said collet and means on said shank to locate said shank selectively in one of two positions apart.

3. A device as defined in claim 2 in which means is provided for mutually guiding and locking said blocks relative to each other comprising an interlock rib on one of said blocks, and means on the other of said blocks forming an interlock groove, one side of said groove being formed by a side plate movable transversely of said other block, and means to move said side plate to a clamping position against said interlock rib.

4. A device as defined in claim 3 in which the side plate is engaged longitudinally with said other block by a rib and groove connection.

5. An apparatus for facilitating the faceting of gem stones in oval shapes which comprises:

(a) a vertical mast support,

(b) a horizontal moving cutting surface adjacent said support,

(c) a supporting arm mounted to project over said surface and for movement on a vertical axis relative to said mast and having a dop support portion manually rotatable to positions about the axis of the arm,

(d) a dop holder on said dop support portion including a shank,

(e) a dop for receiving and holding a gem, and

(f) means connecting said shank and said dop to permit selective and adjustable lateral movement of said dop relative to the axis of said shank to move the axis of said dop relative to the axis of said shank in coincident or spaced parallel positions wherein gems may be faceted with an oval contour.

6. A device as defined in claim 5 in which the means connecting the shank and the dop comprises a pair of mutually slidable blocks mounted respectively on said shank and said dop and joined in a sliding joint to permit said relative lateral motion, and means to lock said blocks in selective adjusted positions.

References Cited UNITED STATES PATENTS 374,743 12/1887 Jones. 1,047,532 12/1912 Johnson. 1,153,673 9/1915 Bryant 279-6 1,838,423 12/1931 Loesser 5l229 2,779,138 1/1957 Collar 5l229 X 3,098,327 7/1963 Malin 51--229 X 3,135,073 6/1964 Odle 5l229 HAROLD D. WHITEHEAD, Primary Examiner.

US. Cl. X.R. 5 l-229 

